A variety of technologies are in play in this rapidly evolving new industry. Virtually all of the major automakers, along with several start-up companies, are developing one type of plug-in vehicle or another.
Some hybrid vehicles will employ a generator that kicks in to replenish vehicle’s batteries when depleted. If driven within the range of the car’s batteries – anywhere from 40-100 miles, depending on the manufacturer – a plug-in hybrid vehicle’s electric motor is the sole source of its propulsion.
Also under development are true all-electric cars, which, as the name would imply, are powered solely by an electric charge provided by the car’s battery. Batteries in both hybrid plug-in and all-electric vehicles, are made from either nickel metal hydride or lithium ion, and are regarded as more environmentally friendly than lead-based batteries used as conventional car batteries. Both types of batteries can be recharged when plugged into a standard power outlet.
Most hybrid and all-electric vehicles also employ a form of regenerative braking, meaning that instead of the electric motor driving the wheels, the wheels drive the motor, which then functions as a generator, converting energy normally wasted into electricity that is stored in the car’s battery until needed.
Automatic start and shut off functions also eliminate energy from being wasted when the vehicle is idling; when the car stops, so too does the engine and electric motor. The engine is automatically restarted when the driver presses the accelerator. (Systems that run the vehicles’ radio and air conditioner typically continue to function when the engine and motor are switched off.)
Several major automakers plan to roll out an array of plug-in vehicles, including both hybrid and all-electric models, as early 2010. To be sure, a great deal of work remains to be done to make these vehicles viable on a large scale, but momentum is clearly building for widespread adoption of a new generation of vehicles powered by electricity.
Several companies are making progress on the infrastructure networks to keep on-the-go plug-in vehicle drivers moving. One system features charging stations where subscribing drivers can plug in their vehicles in for a quick charge. Also in the works is an automated system that would enable drivers to swap a depleted battery for a fully charged one in about the time it takes to fill up a tank of gas.
Deployment of so-called “smart grid” technology also has the potential to allow plug-in vehicles to deliver energy stored in their batteries back to the power grid, providing grid operators another important tool in matching the supply and demand for electricity and maintaining system stability.